Counting apparatus for counting objects by means of a shadow measurement

Abstract

A counting apparatus for counting objects, such as chicks, passed in succession over a conveyor belt through a light beam present between a light source and a photodetector, in which the photodetector produces a detection signal upon each passage of an object through the light beam, which detection signal is applied to a voltage-to-frequency converter for conversion into a frequency varying in accordance with the magnitude of the detection signal, and which detection signal is also applied to a pulse former for conversion into a count pulse whose width is indicative of the period of time required for an object to pass by; wherein the number of cycles of the frequency is counted in a data counter during the period of time that a count pulse is present, and the count pulse is applied to an object counter in response to the data counter having counted a given number of cycles.

I claim: 
     
       1. A counting apparatus for counting objects passed in succession through a light beam present between a light source and a photodetector, in which the photodetector produces a detection signal upon each passage of an object through the light beam, the magnitude of which detection signal depends on the amount of light received by the photodetector and which detection signals are applied to an object counter for counting the number of objects so passed, characterized in that said counting apparatus includes a plurality of light receptors (12) for receiving the light beam (7,8), which receptors (12) are mounted, in-line vertically, the changes in the intensity of the collected light being detected by said photodetector (14); a voltage-to-frequency converter (21) joined to said photodetector for converting the detection signals (D, Da) into a frequency (F) varying in accordance with the magnitudes of the detection signals; a pulse former (22) also joined to said photodetector for converting the detection signals (D, Da) into count pulses (P) whose width is indicative of the period of time required for an object (15) to pass by; and a data counter (27) operatively connected to said converter (21) and the pulse former (22) of cycles (Fs) of said frequency (F) during the period of time that a count pulse (P) is present, an object pulse (Y) being applied from the data counter (27) to said object counter (38) in response to the data counter having counted a given number of said cycles (Fs). 
     
     
       2. A counting apparatus according to claim 1, characterized in that said data counter (27) includes a measuring counter (30) for establishing and storing therein the average number of cycles (Fs) per object (15) as determined on the basis of a number of objects passing by said photodetector (14), and a comparator (29) for comparing said stored average number of cycles (Fs) to the number of cycles (Fs) occurring in response to the passage of each object (15) to be counted, said comparator further being operative to produce at least one object pulse (Y) if the latter number is at least equal to or higher than said stored average number. 
     
     
       3. A counting apparatus according to claim 1, characterized in that said measuring counter (30) includes a monitoring circuit (32) for determining an average measuring value on the basis of a given number of objects, to which end said monitoring circuit (32) produces a release pulse (G1) upon the initiation of the determination procedure and produces an inhibit pulse (G2) after said given number of objects has passed by said photodetector (14); a gating circuit 33 for passing the cycles (Fs) to be counted as caused by said given number of objects, which gating circuit (33) is released and inhibited by said release pulse (G1) and said inhibit pulse (G2), respectively, produced by said monitoring circuit (32); an average value divider (34) responsive to said inhibit pulse (G2) for dividing the total number of cycles (Fs) passed by said gating circuit (33) by the total number of count pulses (P) as corresponding to said given number of objects; and an average value memory (35) in which the resultant quotient (Z) is stored. 
     
     
       4. A counting apparatus according to claim 3, characterized in that said data counter (27) includes a circuit arrangement (31) composed of a value adjusting circuit (37) and a summing circuit (36), in which circuit arrangement (31) the value representing the average number (Z) of cycles (Fs) stored in said average value memory (35) can be changed by means of said value adjusting circuit (31) into at least one other value, which at least one other value is applied to said comparator (29), so that when the passage of an object causes the application of said comparator (29) of a number of cycles (Fs) differing from said average number stored in said average value memory (35), an object pulse (Y) is produced by said comparator (29) only if said number of cycles (Fs) is at least equal to said other value applied to said comparator (29) through said summing circuit (36). 
     
     
       5. A counting apparatus according to claim 1, characterized in that the cycles (Fs) are applied from said voltage -to-frequency converter (21) to said data counter (27) through one of the inputs of a gating circuit (26) having two inputs and one output, and the count pulses (P) are applied to the other of said inputs of said gating circuit (26), the leading edge and the trailing edge of each one of said count pulses (P) being operative to release and inhibit, respectively, said gating circuit (26), said circuit (26) having its output connected to said data counter (27). 
     
     
       6. A counting apparatus according to claim 1, characterized in that said voltage-to-frequency converter (21) produces output signals (F) in response to the detection signals transgressing a predetermined value in upward sense and said converter (21) inhibits output signals (F) in response to said detection signals transgressing said value in downward sense, and that the leading and trailing edges of the count pulses (P) produced by said pulse former (22) may likewise be defined as occurring in response to said detection signals transgressing said predetermined value in upward sense and in downward sense, respectively. 
     
     
       7. A counting apparatus according to claim 1, characterized in that the frequency produced by said voltage-to-frequency converter (21) is directly proportional to the height of the shadow area cast by an object (15) on said light receptors (12). 
     
     
       8. A counting apparatus according to claim 1, characterized by the provision of a voltage control device (23) for said light source (5), which device (23) includes a regulating circuit (24) for regulating the supply voltage (L) of said light source (5), said detection signals (Da) being applied to said regulating circuit (24) in order to so regulate said voltage (L) of said light source (5) that said photodetector (14) produces a predetermined quiescent detection signal when no object passes thereby; and a set-reset circuit (25) to which said count pulses (P) are applied, which circuit (25) is responsive to the leading edge and the trailing edge of a count pulse (P) to apply an inhibit signal and a release signal, respectively, to said regulating circuit (24). 
     
     
       9. A counting apparatus according to claim 8, characterized in that said voltage control device (23) produces an alarm pulse (A) in response to said supply voltage (L) being re-adjusted by said regulating circuit (24) so that it exceeds a maximum value, which alarm pulse is applied to an alarm indicator (32). 
     
     
       10. A counting apparatus according to claim 8, characterized by the provision of an information panel 40 connected to said data counter (27), said object counter (38) and said voltage control device (23) for the visual reproduction of the information provided by said counter, said object counter and said voltage control device . 
     
     
       11. A counting apparatus according to claim 1, characterized in that said light beam (7,8) is directed in vertical sense through a vertical beam slot (9) onto said receptors (12). 
     
     
       12. A counting apparatus according to claim 1, characterized in that said light receptors (12) are optical fibers. 
     
     
       13. A counting apparatus according to claim 2 characterized in that after counting a predetermined number of object pulses (Y) produced by said comparator (29), said object counter (38) applies a control pulse (M) to a control mechanism for actuating an object packaging device connectable to the counting apparatus.